Effect of a low-intensity resistance exercise programme with blood flow restriction on growth hormone and insulin-like growth factor-1 levels in middle-aged women
The effect of a 12-week low-intensity resistance exercise programme with blood flow restriction (LI-BFR) on growth hormone (GH) and insulin-like growth factor-1 (IGF-1) levels in middle-aged women (52.7±7.8 years) was examined. Subjects (N=44) were randomly assigned to the following five groups: control group (CG; n=8), low-intensity (40% of 1RM) resistance exercise group (LI; n=9), high-intensity (70% of 1RM) resistance exercise group (HI; n=9), low-intensity (20% of 1RM) resistance exercise group with a 5% reduction in cuff circumference for blood flow restriction (LI-5% BFR; n=7), and a low-intensity (20% of 1RM) resistance exercise group with a 3% reduction in cuff circumference (LI-3% BFR; n=11). Subjects completed pre- and post-assessments of body weight, percentage body fat, waist-to-hip ratio, muscle strength, GH hormone and IGF-1 levels. A significant effect (p<0.05) was observed for waist-to-hip ratio, GH, IGF-1, biceps curls, triceps extensions, leg curls and leg extensions. A significant elevated GH level was observed in HI and LI-5% BFR groups when compared with the control group (p<0.05). A significant increase in IGF-1 levels was observed in the HI, LI-5% and LI-3% BFR groups when compared with the LI group (p<0.05). Portable cuffs reducing arm and thigh circumferences by 5% were effective in improving GH and IGF-1 levels in middle-aged women.
Key words: Blood flow restriction; Growth hormone; Insulin-like growth factor-1; Resistance exercise; Middle-aged women.